Conformational changes in transfer RNA. I. Equilibrium theory

We report the results of semi-empirical calculations describing thermodynamic properties of transfer RNA conformations. The most important new features of the procedure are: (1) the use of parameters obtained from model oligoribonucleotides to evaluate the free energy of helical regions and small hairpin loops, and (2) the use of a model which is somewhat more realistic than the freely jointed chain for evaluating internal loops and intermediate size hairpin loops. The new parameters lead to important quantitative and qualitative differences from predictions which would have been made in the past and lead to a priori predictions of tRNA melting temperatures which are within about 6°C of the experimental values. The results suggest the following conclusions: (1) The early melting transition observed in several tRNA's is partly the result of tertiary unfolding, and partly the result of the loss of some secondary structure. (2) The part of the secondary structure which melts during the early transition is different for different tRNA's. For fMet and Tyr from E. coli, the calculations predict that the dihydrouradiene arm melts out early. For yeast Phe the acceptor stem and anticodon helix melt first. (3) The results also suggest the possibility that tertiary unfolding and early secondary structural melting do not occur independently but are coupled, so that the two types of structure are probably mutually stabilizing.     

LncRNAs Expression in Preeclampsia Placenta Reveals the Potential Role of LncRNAs Contributing to Preeclampsia Pathogenesis

Background

Long non-coding RNAs (lncRNAs) are an important class of pervasive genes involved in a variety of biological functions. They are aberrantly expressed in many types of diseases. In this study, we aimed to investigate the lncRNA profiles in preeclampsia. Preeclampsia has been observed in patients with molar pregnancy where a fetus is absent, which demonstrate that the placenta is sufficient to cause this condition. Thus, we analyzed the lncRNA profiles in preeclampsia placentas.

Methodology/Principal Findings

In this study, we described the lncRNA profiles in six preeclampsia placentas (T) and five normal pregnancy placentas (N) using microarray. With abundant and varied probes accounting for 33,045 LncRNAs in our microarray, 28,443 lncRNAs that were expressed at a specific level were detected. From the data, we found 738 lncRNAs that were differentially expressed (≥1.5-fold-change) among preeclampsia placentas compared with controls. Coding-non-coding gene co-expression networks (CNC network) were constructed based on the correlation analysis between the differentially expressed lncRNAs and mRNAs. According to the CNC network and GO analysis of differentially expressed lncRNAs/mRNAs, we selected three lncRNAs to analyze the relationship between lncRNAs and preeclampsia. LOC391533, LOC284100, and CEACAMP8 were evaluated using qPCR in 40 preeclampsia placentas and 40 controls. These results revealed that three lncRNAs were aberrantly expressed in preeclampsia placentas compared with controls.

Conclusions/Significance

Our study is the first study to determine the genome-wide lncRNAs expression patterns in preeclampsia placenta using microarray. These results revealed that clusters of lncRNAs were aberrantly expressed in preeclampsia placenta compared with controls, which indicated that lncRNAs differentially expressed in preeclampsia placenta might play a partial or key role in preeclampsia development. Misregulation of LOC391533, LOC284100, and CEACAMP8 might contribute to the mechanism underlying preeclampsia. Taken together, this study may provide potential targets for the future treatment of preeclampsia and novel insights into preeclampsia biology.     

Cancer-initiating cells derived from human rectal adenocarcinoma tissues carry mesenchymal phenotypes and resist drug therapies

Accumulating evidence indicates that cancer-initiating cells (CICs) are responsible for cancer initiation, relapse, and metastasis. Colorectal carcinoma (CRC) is typically classified into proximal colon, distal colon, and rectal cancer. The gradual changes in CRC molecular features within the bowel may have considerable implications in colon and rectal CICs. Unfortunately, limited information is available on CICs derived from rectal cancer, although colon CICs have been described. Here we identified rectal CICs (R-CICs) that possess differentiation potential in tumors derived from patients with rectal adenocarcinoma. The R-CICs carried both CD44 and CD54 surface markers, while R-CICs and their immediate progenies carried potential epithelial–mesenchymal transition characteristics. These R-CICs generated tumors similar to their tumor of origin when injected into immunodeficient mice, differentiated into rectal epithelial cells in vitro, and were capable of self-renewal both in vitro and in vivo. More importantly, subpopulations of R-CICs resisted both 5-fluorouracil/calcium folinate/oxaliplatin (FolFox) and cetuximab treatment, which are the most common therapeutic regimens used for patients with advanced or metastatic rectal cancer. Thus, the identification, expansion, and properties of R-CICs provide an ideal cellular model to further investigate tumor progression and determine therapeutic resistance in these patients.     

Low electromagnetic field (50 Hz) induces differentiation on primary human oral keratinocytes (HOK)

This work concerns the effect of low frequency electromagnetic fields (ELF) on biochemical properties of human oral keratinocytes (HOK). Cells exposed to a 2 mT, 50 Hz, magnetic field, showed by scanning electron microscopy (SEM) modification in shape and morphology; these modifications were also associated with different actin distribution, revealed by phalloidin fluorescence analysis. Moreover, exposed cells had a smaller clonogenic capacity, and decreased cellular growth. Indirect immunofluorescence with fluorescent antibodies against involucrin and beta-catenin, both differentiation and adhesion markers, revealed an increase in involucrin and beta-catenin expression. The advance in differentiation was confirmed by a decrease of expression of epidermal growth factor (EGF) receptor in exposed cells, supporting the idea that exposure to electromagnetic field carries keratinocytes to higher differentiation level. These observations support the hypothesis that 50 Hz electromagnetic fields may modify cell morphology and interfere in differentiation and cellular adhesion of normal keratinocytes.     

Linkage analysis for prenatal diagnosis in a familial case of Stickler syndrome

The Stickler syndrome is among the most common heritable disorders of connective tissue. The syndrome fully expressed clinical phenotype includes the degeneration of the vitreous gel and retina, frequently associated with myopia, accompanied by non-ocular features, such as craniofacial dysmorphisms or malformations, hearing impairment, skeletal dysplasia and progressive arthropathy. So far, mutations at three collagen loci, COL2A1, COL11A1 and COL11A2, have been found in Stickler syndrome patients, with about two thirds of investigated familial cases found to be associated to COL2A1 gene mutations. We report on a three generation family in which a diagnosis of Stickler syndrome was made and linkage analysis suggested COL2A1 to be the causing gene. These data permitted us to perform two prenatal diagnosis analysing the 3'VNTR polymorphism of the involved gene on amniocytes' DNA and to provide the family with genetic counselling and paediatric support at the delivery.